FI112683B - Control arrangement and method for controlling the transverse property profile of a product web running through a paper / cardboard or finishing machine - Google Patents

Description

1 <Ί <''. · '~ 7 1 I L Ο Ο Ο Adjustment Arrangement and Method for Adjusting the Transverse Specific Profile of a Product Web Passing Through a Paper / Cardboard or Post Processing Machine

The present invention relates to a control arrangement in a paper / board or postprocessor 5, which is implemented as a closed control circuit and is intended to control at least one device affecting the desired transverse property profile of the web passing through the machine. comprises a measuring apparatus 10 located downstream of said at least one device for measuring a transverse property profile of the web and a calculating unit for calculating new setpoints of said at least one device on the basis of the measurement data received and feeding the obtained setpoints to the actuators of said device. The invention further relates to a method for adjusting a transverse property profile of a product web passing through a paper / board or post-processing machine by controlling at least one device affecting the transverse property profile after said at least one device according to at least one measurement the transverse property profile of the active members in the device 20.

The paper / board machine and the paper finishing machine have a variety of devices which * influence the property profile of the product web passing through that machine in the transverse direction. Such devices include e.g. a headbox lip opening that influences 25 grammage adjustment; a compression nipple, a steam box and / or an inflatable red heater, which act to effect e.g. kosteusprofiiiiin; calendars that influence things like the thickness and gloss of the product web; and a coating machine, which may be followed by a paper machine or • '. as a separate machine and acting on the coating. In addition, electrically powered induction heating devices controlling the line pressure profile of the 30 calendering nips can be fitted to the calender rolls.

One application for adjusting the lip opening of the headbox for adjusting the basis weight is shown in the applicant's previous Finnish patent 85731 and Figure 1 illustrates various applications of the control system and actuator controller of that patent on a paper / board machine and after finishing.

For adjusting the moisture profile of a paper / board web, adjusting systems are known in which a measuring bar measures the transverse humidity profile of a dry end of a papermaking machine near the machine reel, and the resulting measurement signal adjusts Finnish Utility Model Application No. U960390 describes the use of a long nip press to adjust the transverse humidity profile of the web 10. In this solution, the loading nipples of the long nip press include two substantially parallel rows of loading cylinders, of which the pressures of the loading cylinders of at least one row are individually or individually adjustable by pressure divider.

15 Applicant's earlier Finnish Patent Publication 76872 discloses a method and apparatus for guiding a zone-controlled roll in a transverse direction of the material path. Such zone-adjustable rolls can be used as a dewatering press nip, leveling nip, or calendering nip with a counter roll. These deflection compensated rolls have loading elements supported on the central axis, grouped into zones of desired width along the length of the roll.

•, 't: Calender rolls affect paper or board thickness uniformity, gloss, smoothness, moisture, and pulp. Traditionally, the transverse direction: "These characteristic profiles have been influenced by hot / cold air jets, induction coils, and / or hydraulic zone adjustment. Hot / cold air jets have a ratio of: relatively slow in operation and reaching the final temperature normally takes some tens of minutes The hot / cold air jet is also limited to cases where the surface temperature of the roll is relatively low Induction heating: Can operate at high temperatures but has limited power and, like air jets, it is slow to operate. It also has a large space, can be difficult to install and consumes a lot of energy.It is not possible to provide cooling in induction heating as with air jets, both air jet and induction heating have narrow control zones (actuators are less than 100 mm wide and effective width approx. 600 mm).

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The necessary thermal correction methods have serious side effects: the areas treated by caliber adjustment tend to become more glossy. Thus, the benefits of caliber accuracy cause a loss of gloss in the even.

5 Conventional hydraulic zone adjustment is fast in both raising and lowering the line pressure and has no side effects on the gloss of the paper. However, these zones have a limited transverse profile adjustment capability due to their width, which can be up to 1.5 m. Rolls with individually guided shoes achieve a high hydraulic zone adjustment reaction speed and narrow control zone 10 width.

When adjusting the cross sectional profile of a product web with a multi-zone roll, the speed of adjustment is limited by the measuring device and the processing of the measurement data. Traditionally, the control system has measured several complete cross-sectional profiles of the product web before calculating new actuator set points. This may have been the case in the past because the response times of the actuators have been so long (induction or hot air blast profiling). When profiled on a roll, the response time drops from tens of minutes to seconds or even seconds. In this case, the delay from measurement to adjustment is too long.

Accordingly, it is an object of the present invention to provide an improved control arrangement in a paper / board or finishing machine that allows measurement delays to be further reduced and control operations to be further accelerated. To accomplish this goal, the control arrangement according to the invention is characterized in that: the measuring apparatus is arranged to measure at least two transverse blocks and to send measurement data for each block immediately after the measurement to a calculation unit arranged to immediately calculate the effect on the measured block thereof. new setpoints and send them to said actuators in a transverse property profile of the web:: to adjust the actuating device for that block.

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The method according to the invention, in turn, is characterized in that in the method, the measuring apparatus performs measurements of the transverse property profile in at least two transverse blocks of the web, and the measurement data for each block are immediately sent to the calculating unit

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setting values for the actuators in the area of the measured block and transmitting those values to said actuators for adjusting said at least one device acting on the transverse characteristic profile for that measured block.

5

By performing the adjustment in accordance with the invention in short blocks such that the measuring apparatus measures e.g. 1/4 the width of the edge and immediately transmits that dimension information to the calculation of new setpoints within this range and further optimized and driven, the delay from measurement to adjustment can be substantially reduced. With Van-10, the new optimized profile will run for a minimum of one and a half minutes after the start of the measurement. With the new arrangement, this time can be reduced to about ten seconds or even less. For example, in the case of a thin-shell zone-adjustable roll, the force can be conveyed directly to the line load and no separate optimization is required, but the new setpoints are set directly to 15 runs after the measurement calculation. This allows the profile adjustment to be further accelerated to a few seconds after measurement.

Depending on the profile error and the need for adjustment, the path can be divided into different blocks in order to adjust the problem areas more frequently than others, for example by adjusting the edges more frequently than the center, or if the maximum error exceeds a threshold. In order to minimize the uncertainty of measurement, the desired number of old ones can be used when calculating new setpoints profiles as a basis.

In the following, the invention will be described in more detail in the accompanying drawings with reference to the drawings: *: Figure 1 illustrates an application of prior art adjusting alignment in a paper machine, Fig. 2 schematically illustrates an adjusting alignment according to the invention

The diagrammatically illustrated paper machine of Fig. 1 has a wire section 11 having an upper wire 11a and a lower wire 11b. Headbox 10 supplies a pulp suspension jet of jon '7

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Also, the transverse profile according to the invention is controlled, for the lower part of the wire. This is followed by a two-wire portion 11c. From the bottom wire 11b, the web is detached at the pick-up point P and transferred to the press section on the upper felt 12a, on the underside of which the web W is introduced into the first nip Nj7 of the press section, which is a double felt 12a, 12b.

After the first nip Nj, the web W follows the upper felt 12a, moving to the second nip N2, from which the web W moves to the third nip N3 on the smooth surface of the press roll roll and from there to the fourth press 14a.

Fig. 1 shows an upper drying fabric 14c and a lower drying fabric 14b and the final drying cylinders 14d from the remainder of the front dryer section. Following the drying section is followed by an on-line coating apparatus having blade coaters 16 and a coating nip N1, after which the web W enters into an after-dryer having drying cylinders 16b and a drying wire 16a. Figure 1 shows the final drying cylinders 16b and bottom wire 16c of the after-dryer, after which the web W passes through the calendering nip NK and from there to the pop-up reel 19.

The control system 100 of Fig. 1 and associated actuator guides are applied to lip profiling of headbox 10, control spindle control of steam box 13 between suction nipples Ni and N2, profiling and / or calendering nip of blade coater 20 16, 1 provides a feedback branch: a field branch having properties of the web W, e.g. its transverse thickness profile; is measured by a transverse measuring transducer 15 placed after the drying section, or by a corresponding transducer set after the calender, which may also have a transverse smoothness profile of the web W or the like. ·: Measurement.

Said web profile measuring devices 15 and 18 are connected to the weather system 100 by means of mi and m2. The control system 100 controls various sets of actuators 30 through the connections C1, c2, c3 and C4. Via the links C1, c2 / c3 and Cj, the position and status of the various actuators is also transmitted to the control system 100.

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Fig. 2 schematically illustrates an adjusting arrangement according to the invention for a load-adjustable deflection roller, hereinafter referred to as the TK roll.

2, the TK roll 50 schematically includes the load shoes shown at 53, which are individually adjustable by applying pressure P1, P2, P3, ... Pn. The TK roll 50 forms with the counter roll 60 a nip N through which the product web W is guided. The nip N may be e.g. a dewatering press nip of a paper machine or a calendering nip. The distribution of the line pressure of the nip N in the transverse direction of the web W is controlled by the loading shoes 53. The casing of roll 50 is rotatable about a fixed central axis, and roll 50 is supported by shaft pins 51, 52 formed by the protruding ends of the central shaft, which can be loaded by loading cylinders 71, 72 to load N nip. The loading shoes 53 exert a force effect on the inner surface of the shell of the TK roll 50 by sliding along said si-15 as the shell rotates. The counter roll 60, in turn, is rotatably supported by shaft pins 61, 62 on the bearing supports 63, 64. After the nip N formed by the rolls 50, 60, a measuring apparatus 56 is provided on the machine to measure the profile of at least one property of the web. In the solution of the invention, the measuring apparatus 56 is arranged to perform measurement of certain properties of the product web W in transverse blocks S1-S4 and to transmit measurement data for each block immediately after measurement along unit 70 to calculator 57 arranged to immediately calculate new setpoints ; for the loading pressures P1, P2, P3, ... Pn of the shoes 53. New from unit 57. . The setpoints 25 are transferred to the optimization section 58 associated with the unit of account, where the new setpoints are optimized by taking into account, for example, the cross-effects of the stiffness of the roll 50 casing in the area of other loading shoes. the load value of a given load shoe, as well as any other known factors affecting the set points. The optimized setpoints 30 obtained from the optimization section are set to run, i.e. the pressure line P is supplied with the desired hydraulic medium pressure, which is distributed as individual pressure values for each load shoe 53, e.g., by means of valve control. When the TK roll 50 jacket is sufficiently thin, the force exerted on the shoe 53 by the loading shoes 53 can be considered to be transmitted directly to the liner, eliminating the need for separate optimization and directly setting the 7 1 I L O u o set values from the calculator 57, as depicted

Fig. 2 illustrates a control system according to the invention in connection with the adjustment of the transverse line pressure distribution of the nip formed by the TK roll and the counter roll 5. However, the invention is not limited to use with a TK roll, but is applicable in principle to all types of devices in a paper / board machine and a paper finishing machine that influence the property profile of the product web passing through that machine by means of various actuators or actuators. , various pressing nip rolls, steam box, infrared heater, calender rolls, and coating machine.

One application of the adjusting arrangement and method according to the invention may be, for example, a so-called "nip" of a long nip press equipped with individually controlled load shoes. belttitela.

Claims (9)

1. Control arrangement in a paper / cardboard or finishing machine, which control arrangement is realized as a closed control circuit and is intended to regulate at least one device (50) which influences the desired transverse property profile of the web (W) running through the machine in question. regulating said device belonging to the transverse actuating means (53) arranged in the web, which system has a measuring device (56) arranged in the running direction of the web (W) according to at least one device (50) for measuring the transverse property profile of the web (W) and (57) for counting at least one device (50) of new setpoints on the basis of received measurement data and for feeding new setpoints to the actuator means (53) of the device, characterized in that the measuring device (56) is arranged. in at least two transverse segments (S1-S4) and transmit (70) measurement data belonging to each segment nt (S1-S4) immediately after the measurement to the counter (57), which is arranged to immediately count new setpoints for the actuators (53) arranged in said measured segments (S1-S4) and send them to the actuators (53) to regulating the transverse property profile of the web (W) affecting device (50) with respect to the segment (S1-S4). 20 : 2. Arrangement according to claim 1, characterized in that the measuring apparatus is: arranged to measure in segments, the length of which is about 1/8 - about 1/2 of the width of the web. 3. Arrangement according to claim 1, characterized in that the measuring apparatus is arranged to measure in segments, the length of which is about 1/4 of the width of the web. Arrangement according to any of the preceding claims, characterized in that the device acting on the transverse property profile consists of an inlet carriage's edge strip, an angel sleeve, an induction heater, an infrared heater, a nip roller, a belt roller or a long nip press. coating machine. Arrangement according to any of the preceding claims, characterized in that in the closed control circuit there is also an optimization unit (57) connected to the calculating unit (57) in the L · ϋ ϋ ν_ 'ring part (58) for optimizing the base of the measurement data. the setpoints before feeding to the actuating means (53). A method of controlling the transverse property profile of a product web (W) running through a paper / cardboard or finishing machine by regulating at least one transverse property profile affecting device (50) on the base of one in the product web device (50) provided measuring apparatus (56) outputs measurement data, which measurement data is transmitted (70) to a counting unit (57), and from there, as new setpoints for actuating means (53) arranged in at least one transverse property profile, affecting the device, characterized in the method, the measurement apparatus (56) performs the measurement of the transverse property profile in at least two transverse segments (S1-S4) to the path (W) and measurement data for each segment (S1-S4) is immediately transmitted to the calculator (57). setpoint values are calculated for actuation means within the range of the measured segment and the values in question are transmitted to said actuating means (53) for controlling at least one transverse property profile affecting device (50) for said matte segment (S1-S4). Method according to claim 6, characterized in that in the method the measurements are carried out in segments, the length of which is about 1 / 8-1 / 2 of the width of the web, preferably about 1 / 1/4 of the width of the web. 8. A method according to claim 6 or 7, characterized in that in the method, the adjustable cross-section affecting the device consists of the edge strip of an inlet carriage, an angled casing, an induction heater, an inlet heater, a nip roller, a belt roller; rolled into a longitudinal press or coating machine. Method according to any of claims 6-8, characterized in that in the method an optimizing part (58) adjoining a counter unit (57) is used for optimizing the setpoints prior to their feeding to the actuating means (53).